1. Objective: The learner will realize that certain characteristics are passed from parent to offspring

2. What is Heredity Heredity is the passing of traits from parent to offspring You inherit traits from your parents

3. What are traits? Eye color Hair color Height Weight Body structure Facial features Skin color

4. Body Shape

5. Skin Color

6. Hair Texture

7. Hair color

8. Eye Color

9. What traits did you inherit from your parents? Complete the genetic scavenger hunt with the people at your table. This is today’s science starter. Put your answers in your starter section. List any unusual traits that your group members have on your starter. You have 10 minutes to complete this assignment Be ready to share with class

10. How are traits passed? When organisms reproduce, traits are passed from parent to offspring These traits are carried in DNA, the genetic material found in a cell’s nucleus DNA acts like a blueprint

11. Baker 2003/2004 What are genes? Genes are a segment of DNA on a chromosome that controls a particular trait. Genes are located on the chromosomes in the nuclei. Each organism has a fixed number of chromosomes. Humans have 23 pairs (46) chromosomes. Genetics is the study of how traits are passed on from one generation to another

14. Genetics Hair color is a perfect example of a trait Prince Charming is blond Snow White has dark hair What color hair should their children have?

15. Notes A. Heredity- passing of traits from parent to offspring. –1. Genes on chromosomes control the trait that show up in an organism. –2. The different forms a trait that a gene may have are alleles (inherit one from each parent) -3. During meiosis a pair of chromosomes separate and alleles move into separate cells. 4. Each chromosome now contains one gene for each trait. 5. The study of how traits are inherited is genetics.

17. The study of heredity started with the work of Gregor Mendel and his pea plant garden Mendel was an Austrian Monk that lived in the mid 1800’s

18. Father of Genetics  Monk and teacher.  Experimented with purebred tall and short peas.  Discovered some of the basic laws of heredity.  Studied seven purebred traits in peas.  Called the stronger hereditary factor dominant.  Called the weaker hereditary factor recessive.  Presentation to the Science Society in1866 went unnoticed.  He died in 1884 with his work still unnoticed.  His work rediscovered in 1900.  Known as the “Father of Genetics”.

19. B. Gregor Mendel- the father of genetics 1. Mendel was the first to use the mathematics of probability to explain heredity and to trace one trait for several generations. 2. Made careful use of scientific methods, which resulted in the first recorded study of how traits pass from one generation to the next

20. 3. Hybrid- receives different genetic information for a trait from each parent. A. dominant allele- A trait that covers over, or dominates, another form of that trait –Trait that always shows up, even when only one of the two alleles is in the dominant form –Shown by a capital letter

21. B. Recessive Allele- A trait that is covered over, or dominated, by another form of that trait and seems to disappear –Hidden when the other copy of the gene contains the dominant allele. –A recessive allele shows up only when there is no dominant allele present –Shown with a lower-case letter

23. Steps of Mendel's Experiment

24. Mendel then crossed these second generation tall pea plants and ended up with 1 out 4 being small. x =

25. Mendel’s cross between tall pea plants yielded all tall pea plants. His cross between small pea plants yielded all small pea plants. Mendels’ cross between tall pea plants and small pea plants yielded all tall pea plants. X = x = X =

26. 4. What is a Punnett Square? A. A tool to predict the probability of certain traits in offspring that shows the different ways alleles can combine B. Probability helps you determine the chance that something will happen. C. A way to show phenotype & genotype D. A chart that shows all the possible combinations of alleles that can result when genes are crossed

27. E. Letters stand for dominant and recessive alleles F. An uppercase letter stands for a dominant allele G. Lowercase letters stand for recessive alleles

28. 5. Genotype- the genetic makeup of an organism (genes inherited from parents) a. homozygous- Both alleles [forms of the gene] are the same When offspring inherit two dominant genes, (one dominant gene from each parent) they are said to be homozygous dominant When offspring inherit two recessive genes, (one recessive gene from each parent) they are said to be homozygous recessive

29. b. heterozygous-When alleles occur in different forms –When offspring inherit one dominant gene and one recessive gene, they are said to be heterozygous –Since the dominant gene will be expressed, they are said to be heterozygous dominant

30. 6. PHENOTYPE- Outward physical appearance and behavior of an organism Part the genotype that is visible. Example- color of hair, eye, shape of body, left or right handed.

31. 7. Three Principles of Heredity 1. Traits are controlled by alleles on chromosomes 2. An allele’s effect is dominant or recessive 3. When a pair of chromosomes separate during meiosis the different alleles for a trait move into separate sex cells

32. Introduction to Punnett Squares: A Punnett Square is a chart drawn to determine the probable results of a genetic cross. To be able to draw a Punnett Square, you must know the genotype of both parents. Rr R RRRr r RRrr

33. Baker 2003/2004 Punnett Squares Sample Problem 1. In roses, red flowers are dominant over white flowers. What are the possible offspring when a homozygous red rose is crossed with a homozygous white rose.

34. Baker 2003/2004 homozygous red rose = RR homozygous white rose = ww Generation 1

35. Baker 2003/2004 homozygous red rose = RR heterozygous red rose = Rw homozygous white rose = ww Generation 2

36. Baker 2003/2004 homozygous red rose = RR heterozygous red rose = Rw homozygous white rose = ww Generation 3